There are three common types of windows: double hung, casement, and fixed sash, Double hung windows are the most common; they are the familiar guillotine type window, with sliding top and bottom sash. Casement windows open like doors; some are controlled by cranks, others are controlled by push rods or handles. Fixed sash windows are those that do not open.
Keeping Paint off Window Parts.
Rule one for painting windows: do not get paint in the window works. Usually this simply means keeping paint out of the window channels. It does not matter if you are painting the windows white and the channels are dark stained wood. Resist the urge for uniformity. If you paint the channels, the sash will stick and the windows will not work properly. Either live with the contrast in colors, or paint the channels later.
If you are painting older windows that have sash weight cords or chains, do not paint the cords, chains, or pulleys. If you get paint on these parts, there is a good chance that the windows will not work properly. With casement windows, be sure to keep paint out of the cranks, push rods, handles, and hinges.
Freeing a Stuck Window.
If you find that a window sash was painted shut during the last paint job, free it by using a putty knife or utility knife to cut the paint film binding the sash to the window frame. The window may be painted shut on the inside or outside. Do not bang on the window sash with a hammer. If a window needs a little “persuading,” place a wood block against the sash and tap gently. Be careful not to knock sash corners apart.
Double Hung Windows
If you have not already removed the sash lock hardware, do it now. Place the hardware in plastic bags so small parts and screws do not get lost. Apply only one coat of paint to meeting edges such as sash rails and sash to frame joints. A paint buildup at these joints can prevent the window from opening and closing easily
When you paint the window sash, it is nearly impossible to keep paint off the glass. Fortunately, dried paint comes off glass very easily, so when painting the sash, let the paint lap onto the glass about 1/8 to 1/4 inch. After the paint dries, remove the overlap with a razor blade
Beginning the Upper Sash.
Pull the upper sash down at least an inch to make it easier to paint the top rail. Check the top edge of each sash for any paint buildup. Sand or scrape off fat edges (if any). Paint buildup on the top of either sash can prevent the window from closing properly.
Finishing the Upper Sash.
Push the lower sash all the way up. Then pull the upper sash down to expose the unpainted bottom portion. Finish painting the upper sash. Push the upper sash up to within about an inch of closing to let the top rail dry before pushing it into its channel.
Painting the Lower Sash.
Pull the lower sash down to a comfortable level for painting. Do not push it into the bottom channel. This allows you to paint the entire bottom rail. Paint the lower sash working from top to bottom.
Removing Paint from Glass.
Use a straightedge to score a line along the glass where the paint will end. Then use a window scraper to remove the paint. This tool is designed to hold a single edged razor blade. You can also use a razor blade to remove the paint.
Casement windows are painted in this order: hinge edge; muntins; top, bottom, and sides of sash; and finally the frame. Remember to sand out fat edges before painting. Keep paint out of hinges. When the paint becomes tacky, rotate the sash in and out slightly to break the paint film.
Flashing is a shiny spotting effect that occurs when wet paint is applied over an area of dry paint. The painted area may flash even if you use the same paint, from the same can, applied with the same brush within a half hour. High gloss paints are more prone to flashing than semi-gloss or flat paints, and some colors tend to flash more than others. Keeping a wet edge helps prevent flashing.
Flashing is not much of a consideration for most inferior painting jobs that use low gloss latex paint. However, if semi-gloss or gloss paint is used, you must be careful about keeping a wet edge. Flashing is obvious on touch ups on enamel painted wood trim, such as doors and window frames.
If the paint flashes, there is no way to fix it. Either live with the results or do the job over carefully, while keeping a wet edge.